As one of conventional stroke length adjusting devices may be raised a stroke length adjusting device disclosed in JP Examined Publication No. 47-33812. This stroke length adjusting device is one "which comprises eccentric shaft 1 rotated by a driving member, a member to be reciprocated by the eccentric shaft 1 connecting to the member, and an adjusting member allowing the eccentric shaft 1 to travel along the central axis XX' thereof, characterized in that said eccentric shaft 1 is provided with rotators 52 and 53, on which is mounted inclined shaft 51 in such a manner that both cross each other at a predetermined tilt angle .theta. between the central axis PP' of the inclined shaft 1 and the central axis of the rotators 52 and 53, and a cam 2 is provided, which has hole 54 made therein so as to have said tilt angle to the central axis XX' of said rotators 52 and 53' and mate said inclined shaft 51, whereby said cam 2 is mounted through said hole 54 on said inclined shaft 51 at an angle rectangular to said central axis XX', thus said cam 2 allowing a connecting bar 3 to reciprocate and then said eccentric shaft 1 to travel in the direction of said central axis XX' thereof, so that the stroke length can arbitrarily be regulated regardless of whether it is operated or not".
To be summarized, the above-mentioned stroke length adjusting device is constituted by providing the eccentric shaft 1 between the rotators 52 and 53, which is inclined at a predetermined angle to the central axes of the rotators 52 and 53 and tightly inserted into the hole 54 provided in the cam 2. The up-and-down movement of the rotators 52 and 53 allows the eccentric point of the cam to be changed. The connecting bar connected to the eccentrically rotated cam can be reciprocated at an arbitrarily changed stroke length by adjusting the positions in the vertical direction of the rotators 52 and 53. The two rotators are sustained by respective cylindrical holders in such a manner that the former are mated into the latter.
However, the conventional stoke length adjusting device above has such problems as mentioned below:
(1) A load via the cam is transmitted to the rotators bound to both the ends of the eccentric shaft and then onto the cylindrical holders, in which the rotators are mated. Therefore, in order to transfer the load on the rotators to the holders, the height of the cylindrical rotators is necessary to be made larger. Furthermore, the rotators goes up and down as the eccentric shaft rises up and descends down to change the stroke length of the reciprocated connecting bar. As a result, the thick rotators move up and down at a longer distance, which makes the cylindrical rotator holders longer; PA1 (2) Since a lubricant must be supplied to all the load-burdened positions, lubricant-supplying impellers are required at such positions; PA1 (3) Since a large amount of the lubricant is required, an excess of the lubricant supplied may run out when the rotators are raised up; PA1 (4) Since the structure of the two rotators between which the eccentric shaft is mounted is complicated, the fabrication or assembly thereof requires a large amount of work load; PA1 (5) When the eccentric shaft is raised up and fallen down, a torque is burdened onto a cylindrical worm wheal in which the rotators are inserted to rotate them, and the torque-burdened position is changed as the position of the eccentric shat is moved; and PA1 (6) Since the load applied to the cam causes components of a force to be produced on the eccentric shaft in the vertical direction thereof, a shim adjustment is required at the rotator holders to inhibit the force components in the vertical direction. PA1 the crank member being inclined at a predetermined tilt angle against the central axis of the cylindrical body, thereby allowing the cam to eccentrically move as the crank member travels along the central axis of the cylindrical body and, therefore, provided with a groove-shaped cam-guiding part and further with an outer circumferential surface contacting the inner circumferential surface of the cylindrical body, and PA1 the cam being mounted at the outside of the cylindrical body in the direction rectangular to the central axis of the cylindrical body, and provided with a part to be guided by the cam-guiding part. PA1 the crank member comprising a first recess having a first slope inclined at a predetermined angle against the central axis of the cylindrical body and an inner wall surface facing the first slope, a second recess having a second slope inclined at the same predetermined angle but formed back-to-back with the first slope and an inner wall surface facing the second slope, and an outer circumferential surface sliding on the inner surface of the cylindrical body, PA1 the cylindrical body comprising an inner circumferential surface contacting the outer circumferential surface of the crank member, a first opening having the same width as that of the first recess and facing the first recess, and a second opening having the same width as that of the second recess and facing the second recess, and PA1 the cam being provided with a first projection inserted into the first opening in a mated state and having a slope end surface slidable on the first slope and a second projection inserted into the second opening in a mated state and having a slope end surface slidable on the second slope, and the cam being mounted at the outside of the cylindrical body. PA1 the crank member being provided with a pair of first outer circumferential surfaces slidable on the inner circumference surface of the cylindrical body and formed to be positioned in directions opposite to each other, a pair of bases having flat surfaces formed parallel to each other between the pair of the first outer circumferential surfaces, second outer circumferential surfaces sliding on the inner surface of the cylindrical body and formed at the respective flat surfaces in a pair, and a pair of projections having a first sliding slope inclined at a predetermined angle against the central axis of the cylindrical body, and a second sliding slope inclined at the same predetermined angle as above and formed back-to-back with the first sliding slopes, PA1 the cylindrical body being provided with the inner circumferential surface formed to allow the first and second outer circumferential surfaces to slide thereon, and a pair of a first opening and second opening having the same width as that of the flat surfaces, and PA1 the cam being inserted in a tightly mated state into the first opening at the outside of the cylindrical body, and having a first groove formed to allow the pair of the projections to slide in the cylindrical body as the crank member travels and a second groove formed to allow the bases of the crank member eccentrically rotating as the cylindrical body rotates to move. PA1 the crank member being a cylindrical rod having an outer circumferential surface on which a first groove is formed to slant at a predetermined angle to the central axis of the cylindrical body and a second groove is formed back-to-back with the first groove, the outer circumferential surface slidably contacting the inner circumferential surface of the cylindrical body, PA1 the cylindrical body having the inner circumferential surface contacting the outer circumferential surface of the crank member, and having a first opening and second opening formed so that the cam can be mounted, and PA1 the cam being mounted by inserting it at the outside of the cylindrical body into the first opening and then into the second opening in a mated state, and the cam having a first projection formed thereon so as to be mated in the first groove and a second projection so as to be mated in the second groove.
Therefore, the conventional stroke length adjusting device is complicated in the structure thereof and hence cannot be made in a small size.
The object of this invention is to solve these problems. Another object of this invention is to provide a stroke length adjusting device having a simple structure. A further object of this invention is to provide a smaller-sized stroke length adjusting device as compared with the conventional one. A still further object of this invention is to provide a stroke length adjusting device comprising a less amount of constituting elements to more easily be assembled. An additional object of this invention is to provide a sound stroke length adjusting device having an adequate strength to withstand the torque generated by the movement of the cam.